1. Technical Field
The present invention generally relates to devices and methods for imparting vibrations to a body tissue of a subject and, in particular, to vibration patterns for such devices and methods.
2. Description of Background Art
Vibrations are registered in the mammalian body by mechanoreceptors. There are four main types of mechanoreceptors in the human body: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles that are responsible for detection and communication of mechanical influence. Pacinian corpuscles (also known as lamellar corpuscles) detect rapid vibrations (200-300 Hz). Meissner's corpuscles (also known as tactile corpuscles) on the other hand detect changes in texture (vibrations around 50 Hz) and adapt rapidly. Merkel's discs (also known as Merkel nerve endings) detect sustained touch and pressure and adapt slowly. Ruffini corpuscles (also known as Ruffini's end organs, bulbous corpuscles, and Ruffini endings) are slowly adapting receptors that detect tension deep in the skin. Most studies of mechanoreceptors have been performed on the skin.
Pacinian corpuscles are distributed in connective tissue in various parts of the mammalian body; e.g. in skeletal muscles, in ligaments, in joint capsules, in the periosteum and beneath the interosseous membranes, in the epineurium, in the adventitia of blood vessels, in the pancreas, in the pleura, in the mesentery and in the mesocolon. They are also found in the mammalian skin, where they are localized in the corium and thus deeper than other dermal receptors. In addition, they are densely distributed under the volar surface of the human hand (Zelena J., Nerves and mechanoreceptors: the role of innervations in the development and maintenance of mammalian mechanoreceptors: p. 147 Springer 1994).
Vibration stimulation can be used for various kinds of medical treatment. One example of a vibration device is disclosed in WO 2008/138997. This PCT publication discloses a device for vibration stimulation in a body cavity, such as the nasal cavity or the intestine, of a patient. The device comprises a stimulation member and a vibration generator adapted to bring the stimulation member to vibrate. The device can be arranged in a first state, in which the stimulation member can be introduced via a body opening into a body cavity and a second state, in which the stimulation member is expanded to a volume such that the stimulation member abuts against the tissue within the body cavity. For treatment of rhinitis, the stimulation member may be vibrated at a frequency of about 30-70 Hz for a period of 15 seconds to 7 minutes in the nasal cavity.